Configurable file_descriptors limit for warden container

file_descriptors for a warden container is made configurable through
deployment manifest.
Currently the default is 16384 which is read from the database table
and is not configurable. To configure, cf operator needs to add the
following config variable under cc
cc:
  default_app_file_descriptors: 4096

[#82011156]

app/models/runtime/app.rb

@@ -44,13 +44,13 @@ def after_initialize
                       :state, :version, :command, :console, :debug, :staging_task_id,
                       :package_state, :health_check_type, :health_check_timeout,
                       :staging_failed_reason, :docker_image, :package_updated_at,
-                      :detected_start_command
+                      :detected_start_command, :file_descriptors
 
     import_attributes :name, :production, :space_guid, :stack_guid, :buildpack,
                       :detected_buildpack, :environment_json, :memory, :instances, :disk_quota,
                       :state, :command, :console, :debug, :staging_task_id,
                       :service_binding_guids, :route_guids, :health_check_type,
-                      :health_check_timeout, :docker_image, :app_guid
+                      :health_check_timeout, :docker_image, :app_guid, :file_descriptors
 
     strip_attributes :name
 
@@ -137,6 +137,9 @@ def before_save
       self.stack ||= Stack.default
       self.memory ||= Config.config[:default_app_memory]
       self.disk_quota ||= Config.config[:default_app_disk_in_mb]
+      if Config.config[:default_app_file_descriptors]
+        self.file_descriptors ||= Config.config[:default_app_file_descriptors]
+      end
 
       set_new_version if version_needs_to_be_updated?
 

bosh-templates/cloud_controller_api.yml.erb

@@ -72,6 +72,7 @@ billing_event_writing_enabled: <%= p("cc.billing_event_writing_enabled") %>
 
 default_app_memory: <%= p("cc.default_app_memory") %>
 default_app_disk_in_mb: <%= p("cc.default_app_disk_in_mb") %>
+default_app_file_descriptors: <%= p("cc.default_app_file_descriptors") %>
 maximum_app_disk_in_mb: <%= p("cc.maximum_app_disk_in_mb") %>
 
 request_timeout_in_seconds: <%= p("request_timeout_in_seconds") %>

bosh-templates/cloud_controller_clock.yml.erb

@@ -76,6 +76,7 @@ billing_event_writing_enabled: <%= p("cc.billing_event_writing_enabled") %>
 
 default_app_memory: <%= p("cc.default_app_memory") %>
 default_app_disk_in_mb: <%= p("cc.default_app_disk_in_mb") %>
+default_app_file_descriptors: <%= p("cc.default_app_file_descriptors") %>
 maximum_app_disk_in_mb: <%= p("cc.maximum_app_disk_in_mb") %>
 
 request_timeout_in_seconds: <%= p("request_timeout_in_seconds") %>

bosh-templates/cloud_controller_worker.yml.erb

@@ -72,6 +72,7 @@ billing_event_writing_enabled: <%= p("cc.billing_event_writing_enabled") %>
 
 default_app_memory: <%= p("cc.default_app_memory") %>
 default_app_disk_in_mb: <%= p("cc.default_app_disk_in_mb") %>
+default_app_file_descriptors: <%= p("cc.default_app_file_descriptors") %>
 maximum_app_disk_in_mb: <%= p("cc.maximum_app_disk_in_mb") %>
 
 request_timeout_in_seconds: <%= p("request_timeout_in_seconds") %>

lib/cloud_controller/config.rb

@@ -41,6 +41,7 @@ class Config < VCAP::Config
         optional(:billing_event_writing_enabled) => bool,
         :default_app_memory => Fixnum,
         :default_app_disk_in_mb => Fixnum,
+        optional(:default_app_file_descriptors) => Fixnum,
         optional(:maximum_app_disk_in_mb) => Fixnum,
         :maximum_health_check_timeout => Fixnum,
 

spec/unit/models/runtime/app_spec.rb

@@ -429,7 +429,8 @@ def act_as_cf_admin(&block)
           :staging_failed_reason,
           :staging_task_id,
           :state,
-          :version
+          :version,
+          :file_descriptors
         )
       }
 
@@ -455,7 +456,8 @@ def act_as_cf_admin(&block)
           :space_guid,
           :stack_guid,
           :staging_task_id,
-          :state
+          :state,
+          :file_descriptors
         )
       }
     end
@@ -1640,7 +1642,23 @@ def self.it_does_not_mark_for_re_staging
         end
       end
 
-      describe 'default disk_quota' do
+      describe "default_app_file_descriptors" do
+        before do
+          TestConfig.override({default_app_file_descriptors: 200})
+        end
+
+        it "uses the provided file descriptors limit" do
+          app = App.create_from_hash(name: "awesome app", space_guid: space.guid, file_descriptors: 100)
+          expect(app.file_descriptors).to eq(100)
+        end
+
+        it "uses the default_app_file_descriptors when none is provided" do
+          app = App.create_from_hash(name: "awesome app", space_guid: space.guid)
+          expect(app.file_descriptors).to eq(200)
+        end
+      end
+
+      describe "default disk_quota" do
         before do
           TestConfig.override({ default_app_disk_in_mb: 512 })
         end